The language routers use to talk to each other and agree on which labels to use for specific destinations. 4. Why Use MPLS Today?

Receives a plain IP packet, looks up the destination, and pushes the first label.

An MPLS label is a 32-bit identifier inserted between the Layer 2 header (Ethernet) and the Layer 3 header (IP). This is why MPLS is often called a "Layer 2.5" protocol .

The "gatekeeper" located at the edge of the MPLS network.

Any router capable of performing MPLS switching.

In the mid-1990s, routers struggled to keep up with increasing internet traffic. Standard IP routing required a "longest prefix match" lookup in a routing table for every single packet, which was computationally expensive.

The core concept of MPLS is . Instead of inspecting the IP destination address at every hop, the first router (Ingress) attaches a label to the packet. Subsequent routers simply "swap" that label and forward the packet based on its value.